Stamped rivet

ABSTRACT

A stamped rivet ( 10 ) for the connection of metal sheets ( 12, 14 ) to each other is provided, and includes a shaft ( 16 ) with several circumferential ribs ( 18 ) located one above another on the shaft ( 16 ), a shaft end ( 20 ) for pressing through the sheets ( 12, 14 ) for connection to each other, and a head ( 26 ). An adjacent region ( 30 ) to the shaft end ( 20 ) has no circumferential ribs and has a diameter smaller than an outside diameter (D) of the circumferential ribs. The stamped rivet ( 10 ) is easy to set as the setting device only has to be able to push the stamped rivet ( 10 ) through the sheets ( 12, 14 ) for connection. Sheet material is then forced by plastic deformation into the circumferential grooves ( 38 ) formed between the circumferential ribs ( 18 ).

BACKGROUND

The invention relates to a stamped rivet for connecting metal sheets toone another, having a shaft with several circumferential ribs formed onthe shaft one above the other and with a shaft end for pressing throughthe metal sheets to be connected to one another, with at least allcircumferential ribs contacting the metal sheets having the same outsidediameter, with the shaft being provided with a head opposite the shaftend, said head having a diameter greater than the outside diameter ofthe circumferential ribs, and with an adjacent area to the shaft endbeing free from circumferential ribs.

A stamped rivet is known from U.S. Pat. No. 4,978,270, provided withoutany head and serving for the connection of three metal sheets to oneanother. Its overall length is equivalent to the overall thickness ofthe metal sheets to be connected to one another so that it is flush withthem in the installed state. This known rivet does not only represent astamped rivet but simultaneously an embossed rivet as well. When such astamped/embossed rivet has pressed through the metal sheets to beconnected to one another under the formation of a punched hole,subsequently a groove is embossed around the two ends of the shaft inthe respective neighboring sheet metal, causing material of the metalsheets to enter the circumferential grooves formed between twoneighboring circumferential ribs each under plastic deformation, inorder to form-fittingly connect the three metal sheets and the stampedrivet to one another. Due to the embossing process necessary, such astamped/embossed rivet requires a rivet placing device designedappropriately elaborate. This device must be provided with a stampingtool and a corresponding male counterpart. Additionally, sufficientmaterial can only be deformed into the circumferential grooves when thethree metal sheets to be connected to one another are sufficientlythick. The known stamped/embossed rivet is obviously neither intendednor suitable for the connection of thin metal sheets to one another.

A stamped rivet of the type mentioned in the preamble of claim 1 isknown from EP 1 054 169 A2. This known stamped rivet is astamped/embossed rivet like the above-mentioned known stamped rivet. Dueto the fact that it is provided with a frustum-shaped rivet head, thestamping process operates easier than with the above-mentioned knownstamped rivet because a groove is to be embossed around the shaft endonly. However, in this known stamped rivet, sufficient material can onlybe deformed into the circumferential grooves by way of embossing if themetal sheets to be connected are sufficiently thick.

SUMMARY

The object of the invention is to provide a stamped rivet of the typementioned at the outset, such that it allows a secure connection ofmetal sheets to be provided, particularly of thin metal sheets, in asimple manner.

This object is attained according to the invention with a stamped rivetof the type mentioned in the preamble of claim 1 in which the bottom ofthe head facing the shaft is planar, and that the neighboring area ofthe shaft end has a smaller diameter than the outside diameter of thecircumferential ribs.

When the stamped rivet according to the invention is installed, at firstthe neighboring area of the shaft end enters the metal sheets to beconnected to one another and pre-punches a punched hole, which has asmaller diameter than the outside diameter of the circumferential ribs.When subsequently the area of the shaft extending to the bottom of thehead, in which the circumferential ribs are located, enters the punchedhole, the hole is widened with sheet metal material entering thecircumferential grooves formed between the circumferential ribs and,this way, finally the stamped rivet and the metal sheets are connectedto one another in a form-fitting manner, when the head contacts with itsbottom the metal sheets to be connected. Although the draw-out strengthof such a rivet is smaller than in the above-described prior art, theplacing of the stamped rivet according to the invention is considerablyeasier than in the known stamped rivets, because the stamped rivetaccording to the invention only needs to be pressed through the metalsheets to be connected and requires no embossing processes. The rivetplacement tool can therefore be designed in an appropriately simplefashion and, in the simplest case, be a hammer operated manually. Thestamped rivet itself is not being deformed during the placement process,similar to prior art.

The advantageous embodiments of the stamped rivet according to theinvention form the objects of the sub claims.

When in an embodiment of the stamped rivet according to the inventionthe neighboring area has a cylindrical section, which transitions via asection that conically widens in the axial direction towards the headinto an entry rib extending in the circumferential direction, with theoutside diameter being smaller than the outside diameter of thecircumferential ribs, a defined punched hole can be produced, whichincreasingly widens, with the help of the conical section, to theoutside diameter of the entry rib and finally is widened by thecircumferential ribs to their outside diameter.

When in another embodiment of the stamped rivet according to theinvention the diameter of the cylindrical section is smaller than thesmallest diameter of the shaft between the circumferential groovesformed between the ribs, it is ensured that finally the metal sheets areconnected sufficiently tight in a form-fitting manner at the end.

When in another embodiment of the stamped rivet according to theinvention the cylindrical section extends in the direction opposite tothe head to the shaft end, the cylindrical section forms a stamp member,which can be provided with sharp edges at the circumference in order tofacilitate and optimize the stamping process.

When in another embodiment of the stamped rivet according to theinvention the cylindrical section in the direction opposite to the headconverges into a conical point, the stamped rivet can be pressed withlittle force through the metal sheets to be connected to one another.

When in another embodiment of the stamped rivet according to theinvention the circumferential ribs are triangular shaped incross-section, the sheet metal material should most easily be able toenter under plastic deformation the circumferential grooves formedbetween the circumferential ribs.

When in another embodiment of the stamped rivet according to theinvention the circumferential ribs in the cross-section are in atrapezoidal shape, the number of the circumferential ribs can beadjusted by selecting the width of the narrow side of the trapezoid inthe available area depending on the purpose intended.

When in another embodiment of the invention the circumferential groovesformed between the circumferential ribs are V-shaped in thecross-section, the sheet metal material can easily penetrate underplastic deformation to the bottom of the circumferential grooves.

When in another embodiment of the stamped rivet according to theinvention the bottom of the head converges into a cylindrical exit rib,which has the same outside diameter as the circumferential ribs, it isensured that sheet metal material can penetrate under plasticdeformation into the circumferential groove adjacent to the exit rib.

When in another embodiment of the stamped rivet according to theinvention the circumferential ribs are formed in an area adjacent to thebottom of the head, with the axial length of said area being half aslong as the total length of the shaft, the metal sheets to be connectedto one another can vary in their thickness within a relatively widerange.

When in another embodiment of the stamped rivet according to theinvention the overall length of the shaft is three to four times thetotal thickness of the metal sheets to be connected to one another, theshaft section not provided with circumferential ridges is alsosufficiently long to securely pre-form a punched hole, which is broughtinto its final form by the circumferential ridges.

BRIEF DESCRIPTION FO THE DRAWINGS

In the following, exemplary embodiments of the invention are explainedin greater detail using the drawings. They show:

FIGS. 1 a and 1 b shows a side view and/or top view of a first exemplaryembodiment of a stamped rivet according to the invention;

FIG. 2 shows the stamped rivet according to FIG. 1 in a posted state;

FIGS. 3 a and 3 b show a side view and/or top view of a second exemplaryembodiment of the stamped rivet according to the invention;

FIGS. 4 a and 4 b show a side view and/or top view of a third exemplaryembodiment of the stamped rivet according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 a and 1 b show a side view and/or top view of a first exemplaryembodiment of a stamped rivet according to the invention, indicated as10 in its entirety, which is shown in FIG. 2 in a longitudinalcross-section and in an installed state, in which it connects in aform-fitting manner two metal sheets 12, 14 to one another. The stampedrivet 10 has a shaft 16, several circumferential ribs 18 formed at theshaft 16 above one another, and a shaft end 20 for pressing through themetal sheets 12, 14 to be connected to one another. The two axiallyexterior circumferential ribs are embodied differently. They are anentry rib 22 and an exit rib 24, which will be explained in greaterdetail below. All circumferential ribs 18 engaging with the metal sheetsincluding the exit rib 24 have the same outside diameter D.

Opposite to the shaft end 20, the stamped rivet 10 is provided with ahead 26. The diameter of the head 26 exceeds the outside diameter D ofthe circumferential ribs 18. A bottom 28 of the head 26 facing the shaft16 is provided with a planar shape so that a circular plane surface isprovided for contacting the metal sheet 12. A neighboring area of theshaft end 20, indicated as 30 in its entirety, is free fromcircumferential ribs 18 and has a smaller diameter than the outsidediameter D of the circumferential ribs 18. The neighboring area 30 isprovided with a cylindrical section 32, which converges via a section34, conically widening in the axial direction toward the head 26, intothe entry rib 22 which extends in the circumferential direction, theentry rib having an outside diameter, which is smaller than the outsidediameter D of the circumferential ribs 18, as easily discernible fromFIGS. 1 and 2. The transfer from the cylindrical section 32 to theconical section 34 is rounded, as is discernible from the figures. Thecylindrical section 32 has a diameter, which is smaller than thesmallest diameter d of the shaft 16 between the circumferential grooves18. The entry rib 22 is the rib, which first enters the punched hole,pre-punched by the cylindrical section 32, before subsequently thecircumferential ribs 18, having a larger outside diameter D, enter thepunched hole. Finally the exit rib 24 enters, being the last ribextending in the circumferential direction that penetrates the punchedhole.

In the exemplary embodiment shown in FIG. 1, the cylindrical section 32extends to the shaft end 20, opposite to the direction of the head 26.FIGS. 3 a and 3 b show a side view and/or top view of a second exemplaryembodiment of a stamped rivet according to the invention, indicated as10′ in its entirety, which differs from the stamped rivet 10 only in thefact that the cylindrical section 32′ has a shorter axial length thanthe cylindrical section 32 and that the cylindrical section 32′converges into a conical point in the opposite direction of the head 26.The other parts of the second exemplary embodiment are identical to thefirst exemplary embodiment. In the stamped rivet 10 as well as in thestamped rivet 10′, the circumferential ribs 18 and/or 18′ have atriangular cross-section.

FIGS. 4 a and 4 b show a side view and/or top view of a third exemplaryembodiment of a stamped rivet according to the invention, indicated as10″ in its entirety, which is trapezoidal in its cross-section. Theother parts of the exemplary embodiment according to FIG. 4 areidentical to the exemplary embodiment according to FIGS. 1 and 2 andtherefore need no further explanation.

In all three exemplary embodiments, the circumferential grooves 38, 38′,and 38″ formed between the circumferential ridges 18, 18′, and 18″ areV-shaped in their cross-section. Similarly, in all exemplary embodimentsthe head 26, 26′, and 26″ converges into the cylindrical exit rib 24,24′ and/or 24″, which has the same outside diameter D, D′, and/or D″ asthe circumferential ribs 18, 18′, and/or 18″. The circumferential ribs18, 18′, 18″ are formed in an area 40, 40′ and/or 40″ adjacent to thebottom of the head 26, 26′, 26″, with its axial length being half aslong as the overall length of the shaft 16, 16′ and/or 16″. The overalllength of the shaft 16, 16′, 16″ amounts to three to four times theoverall thickness of the metal sheets 12, 14 to be connected to oneanother.

1. A stamped rivet for connecting metal sheets to one another,comprising a shaft, several circumferential ribs provided one above theother on said shaft, and a shaft end for pressing through the metalsheets to be connected to one another, with at least all of thecircumferential ribs engaging the metal sheets having an outsidediameter that is the same, with the shaft, opposite to the shaft end,being provided with a head having a larger diameter than the outsidediameter of the circumferential ribs, and with an adjacent area of theshaft end being free from circumferential ribs, wherein a bottom (28) ofthe head (26, 26′, 26″) facing the shaft (16, 16′, 16″) is planar and anadjacent area (30) to the shaft end (20) has a smaller diameter than anoutside diameter (D, D′, D″) of the circumferential ribs (18, 18′, 18″):2. A stamped rivet according to claim 1, wherein the adjacent area (30)has a cylindrical section (32, 32′, 32″) converging via a conicallywidening section (34, 34′, 34″) in a direction of the head (26, 26′,26″) into an entry rib (22, 22′, 22″) which extends circumferentiallyand has an outside diameter smaller than the outside diameter (D, D′,D″) of the circumferential ribs (18, 18′, 18″).
 3. A stamped rivetaccording to claim 2, wherein the diameter of the cylindrical section(32, 32′, 32″) is smaller than a smallest diameter (d) of the shaft (16,16′, 16″) at circumferential grooves (38, 38′, 38″), which are formedbetween the ribs (18, 18′, 18″, 22, 22′, 22″, 24, 24′, 24″).
 4. Astamped rivet according to claim 2, wherein the cylindrical section (32,32″) extends in a direction opposite to the head (26, 26″) to the shaftend (20, 20″).
 5. A stamped rivet according to claim 3, wherein thecylindrical section (32′) converges into a conical point (36) in thedirection opposite to the head (26′)
 6. A stamped rivet according toclaim 3, wherein the circumferential ribs (18, 18′) have a triangularcross-section.
 7. A stamped rivet according to claim 3, wherein thecircumferential ribs (18″) have a trapezoidal cross-section.
 8. Astamped rivet according to claim 3, wherein the circumferential grooves(38, 38′, 38″) formed between the circumferential ribs (18, 18′, 18″)have a V-shaped cross-section.
 9. A stamped rivet according to claim 1,wherein the head (26, 26′, 26″) converges at a bottom (28) thereof intoa cylindrical exit rib (24, 24′, 24″), which has an outside diameter (D)that is the same as the circumferential ribs (18, 18′, 18″).
 10. Astamped rivet according to claim 1, wherein the circumferential ribs(18, 18′, 18″) are formed in an area adjacent to the bottom (28) of thehead (26, 26′, 26″), which has an axial length half as long as anoverall length of the shaft (16, 16′, 16″).
 11. A stamped rivetaccording to claim 10, wherein the overall length of the shaft (16, 16′,16″) exceeds an overall thickness of the metal sheets (12, 14) to beconnected three to four fold.